Umbraco-CMS/src/Umbraco.Core/PublishedModelFactoryExtensions.cs

using System;
using System.Collections.Generic;
using Umbraco.Core.Models.PublishedContent;

namespace Umbraco.Core
{
    /// <summary>
    /// Provides extension methods for <see cref="IPublishedModelFactory"/>.
    /// </summary>
    public static class PublishedModelFactoryExtensions
    {
        /// <summary>
        /// Returns true if the current <see cref="IPublishedModelFactory"/> is an implementation of <see cref="ILivePublishedModelFactory"/>
        /// </summary>
        /// <param name="factory"></param>
        /// <returns></returns>
        public static bool IsLiveFactory(this IPublishedModelFactory factory) => factory is ILivePublishedModelFactory;

        /// <summary>
        /// Executes an action with a safe live factory
        /// </summary>
        /// <remarks>
        /// <para>If the factory is a live factory, ensures it is refreshed and locked while executing the action.</para>
        /// </remarks>
        public static void WithSafeLiveFactory(this IPublishedModelFactory factory, Action action)
        {
            if (factory is ILivePublishedModelFactory liveFactory)
            {
                lock (liveFactory.SyncRoot)
                {
                    //Call refresh on the live factory to re-compile the models
                    liveFactory.Refresh();
                    action();
                }
            }
            else
            {
                action();
            }
        }

        /// <summary>
        /// Creates a strongly typed model while checking if the factory is <see cref="ILivePublishedModelFactory"/> and if a refresh flag has been set, in which
        /// case the models will be recompiled before model creation
        /// </summary>
        /// <param name="factory"></param>
        /// <param name="content"></param>
        /// <returns></returns>
        internal static IPublishedContent CreateModelWithSafeLiveFactoryRefreshCheck(this IPublishedModelFactory factory, IPublishedContent content)
        {
            if (factory is ILivePublishedModelFactory liveFactory && _refresh)
            {
                lock (liveFactory.SyncRoot)
                {
                    if (_refresh)
                    {
                        _refresh = false;
                        //Call refresh on the live factory to re-compile the models
                        liveFactory.Refresh();
                    }
                }
            }

            var model = factory.CreateModel(content);
            if (model == null)
                throw new Exception("Factory returned null.");

            // if factory returns a different type, throw
            if (!(model is IPublishedContent publishedContent))
                throw new Exception($"Factory returned model of type {model.GetType().FullName} which does not implement IPublishedContent.");

            return publishedContent;
        }

        /// <summary>
        /// Sets a flag to re-compile the models if the <see cref="IPublishedModelFactory"/> is <see cref="ILivePublishedModelFactory"/>
        /// </summary>
        /// <param name="factory"></param>
        /// <param name="action"></param>
        internal static void WithSafeLiveFactoryRefreshSet(this IPublishedModelFactory factory, Action action)
        {
            if (factory is ILivePublishedModelFactory liveFactory)
            {
                lock (liveFactory.SyncRoot)
                {
                    _refresh = true;
                    action();
                }
            }
            else
            {
                action();
            }
        }

        private static volatile bool _refresh = false;

    }
}